Oil well tool gripping element



Aug. 29, 1950 w, ABEGG 2,520,448

OIL WELL TOOL GRIPPING ELEMENT Filed Aug. 16, 1947 INVENTOR. K644752214.A2204 ATTORNEYS.

Patented Aug. 29, 1950 UNITED STATES PATENT OFFICE QIL WELL TOOLGRIPPING ELEMENT Walter A. Abegg, Los Angeles, Calif., assignor, bymesne assignments, to Abegg & Reinhold (30., Los Angeles, Calif acorporation of California Application August is, 1947, Serial No.769,031

7 Claims. 1

This invention relates to oil well tools, and particularly pertains tooil well tool gripping elements.

At the present time various types of oil well tools are used, such asslips, elevators, rotary tongs and the like, all of which operate on theprinciple of providing an embracing member for a pipe casing or otherelement, and which member is fitted with a surface or elements which areserrated o1- abraded to provide a roughened surface by which acylindrical article or the like is gripped with suflicient friction topermit-the article to be positively turned and supported b the elementcarrying said surface. When the articles to be gripped and turned aretubular there is always the possibility that the gripping action willhave sufficient force to crush the tubular member or weaken its wall,and thus diminish its torsional strength. slips, elevators, and rotarytongs, have been provided with gripping inserts which have been mountedupon the gripping members and have been formed with transverseserrations or with teeth which would impinge against the surfaces of themember to be gripped and which will thus add to the frictionalengagement of the member to be gripped and the gripping structure. Inoil Well practice it is often necessary to provide slips which aresupported within the bowl of a rotary table and which are disposed in anembracing position around the member to be gripped to impart rotarymotion of the table to the member and to support the weight of a drillstring. In present oil well drilling practice drilled holes extend for aconsiderable length, and many drilling operations take place at a depthbeyond ten thousand feet. It is obvious, therefore, that when the weightof the drill string is imposed upon the slip and the abraded elementsthat there is a tendency, and often a possibility, that the teeth orprotuberances forming the gripping surfaces of the slip will be placedunder such a shearing strain as to cause them to be broken off. In viewof this circumstance it is also desirable to make it possible for thegripping elements to be easily removed and replaced. Various structureshave been provided for this purpose, such as those shown in my PatentNo. 2,119,731 entitled Drill Pipe Slip and issued by the United StatesPatent Office on July 7, 1938. It has been found, however, that in viewof present oil well drilling practice in which the wells extend to adepth beyond three miles, the weight imposed upon the teeth orprotuberances is so excessive that the protuberances are broken off. Itis desirable therefore to Heretofore, gripping members, such asprovide atype of gripping element which will not only be sufllciently strong forall normal purposes, such as when used with elevators and rotary tongs,but will also have suflicient strength to support these enormousweights. It is the principal object of the present invention, therefore,to provide a method and means of producing gripping inserts for theaforesaid purposes which will insure that they will have maximumstrength and an emcient gripping surface and will at the same time be ofa design which will lend itself to cheap and efiicient manufacturingoperations.

It is another object of the present invention to provide a method andmeans of making gripping inserts of the character set forth in which thestructure of the steel elements is utilized in the most efficient mannerto obtain strength for the protuberances of the gripping elements.

The present invention contemplates a method and means of making grippingelements from bar stock material in which the elements are formed withdirect relation to the grain of the bar stock and in which the grippingsurfaces of the elements are so designed as to produce a maximumgripping action with a maximum supporting strength so that there willnot be a tendency for the protuberances to shear due to the load imposedupon them.

The invention is illustrated by way of example in the accompanyingdrawing in which:

Figure l is a view showing a slip used in connection with a rotary tablefor gripping and supporting a pipe suspended in a well bore.

Fig. 2 is a view in transverse section through the slip structure asseen on the line 2--2 of Fig. 1 and shows the manner in which thegripping element of Fig. 4 is mounted within the slip structure.

Fig. 3 is a view in front elevation showing one form of gripping elementas used in the slip.

Fig. 4 is a view in transverse section through the gripping element asshown in Fig. 3 and indi cates the specific construction of one :form ofthe gripping element.

Fig. 5 is a view in side elevation showing another form of grippingelement embodying the present invention.

Referring more particularly to the drawing, [0

indicates a section of a drill slip, it being understood however thatwhile this invention is illustrated with relation to drill slips that itmay be used in connection with any other type of gripping structure. Thesection 10 as here shown is formed with a longitudinal portion havingchan- ILQLE H 11 12 in it which are closed at their hothave oppositeparallel portions I3 formed with undercut portions M. The undercutportions It thus make the channels in T-shape, dovetail, or othersuitableshape. It is understood, however, that other types of mountingsmay be used in the present invention, such for example as providingradial bores in the member III to receive shanks 3| shown in Fig. 5. Theslip structure In is here shown as being one of the articulate elementsof a slip designed to fit within the bowl of a, rotary table and hereshown as formed with spaced lugs l6 and I1. The lugs I6 and H aredrilled with aligned bores to receive pins l8. These pins are held inposition by cotters l9. They pass through hinge blocks 20 by which theymay be hinged to other slip elementslll not shown in the drawings.

The slip element is formed with an arcuate wall section 2| shown in thedrawings as having the longitudinal channels II and I2. Mounted withinthe longitudinal channels are gripping elements 22 with which thepresent invention is particularly concerned. These gripping elements arecharacterized as being formed with a gripping face from which projectsone or more concentric circular gripping ridges, here indicated at 23and 24. One form of the gripping element;

as shown in Fig. 2 of the drawings, comprises an enlarged back disc 25which fits into the undercut grooves l4 of the channel and carries onits face an outwardly projecting circular portion which fits between thewalls l3 of the channels. The disc-shaped portion 25 is formed atcertain of its edges with non-circular faces which either engage theside walls of the channels M or engage contiguous gripping elements 22to prevent their rotation. Due to this arrangement the gripping elementsshown in Figs-1 and 2 are held against rotation around their centralaxes and when viewed in a plane normal to the longitudinal axis of amember to be gripped the circular gripping ridges 23 and 24 will liealong an arcuate plane 21 which is struck from the axis of the center ofthe member to be gripped. The cross-section of the ridges 23 and 24 isV- shaped. The taper of the ridges is oppositely from their grippingedges, and in view of the fact that the transverse cross-section of thegripping element lies in an arcuate plane it will be obvious that thecircular ridges 23 and 24 will be of lesser depth at their upper andlower edges than at their sides. This will insure that the ridges willhave a maximum strength. The contacting edges will conform to thecylindrical face of the element to be gripped and will become imbeddedtherein. Attention is directed to the fact that since the concentriccircular gripping ridges present an arc-like structure, both to weightlongitudinally applied and to torque imposed by rotation of the slips,they will provide maximum resistance to shear. should also be pointedout that the area of the continuous circular gripping ridges 23 and 24present a greater strength and resistance to shear than would bepresented if the ridges were uniformly distributed over a grippingsurinvention to form the gripping element of bar steel stock and to cutthe gripping element from longitudinal sections of the stock. Thisinsures that the grain of the steel will extend at right angles to thedirection of the load or shear. It has been found in actual practicethat the longitudinal grain of the steel offers greater resistance toshear strain since the shear force is in a plane normal to the fibers ofthe steel and is not parallel to them. In the present instance thereforeit has been found that bar stock face and were individually formed, asis the case can be used in an automatic screw machine, and thatas it isfed through the machine it may be machined to form the gripping ridgesand may be cut into lengths automatically so that the fibers of thegrain of the steel will extend through'the'gripping member parallel tothe axis of the bar from which it is cut, both in the body of thegripping element and in the ridges.

In the form of the invention shown in Fig. 3 of the drawing it will beseen that the base portion of the gripping elements may be square,octagon, hexagon, or flattened, as indicated at 28, 28a, 28b and 280,and will thus fit conveniently into the channels II and I2 so that thegripping members cannot rotate on their individual axes. In'order toconfine the gripping elements in the channels I l and I2 square-headedlock bolts 23 are carried by the slip element at the upper ends of thechannels, against which the flat faces of the gripping members bear toprevent their rotation. The lower ends of the channels are closed bysome suitable means.

Reference has been had to the capacity of the pp ng edge 23 to. hold thework against movement in either direction longitudinally of the.gripping die series in Fig. 1, and also against rotational movement ineither direction, and to the strength characteristics of the grippingridge or edge by reason of its arch formation. Further detailed analysisof the relation between the work surface and gripping edge, is made withreference to Fig. 3. In the first place, the gripping edge 23 may bedefined as lying in the line of intersection between a largercylindrical surface (that of the work), and a smaller cylindrical planeor surface (passing through the gripping edge 23 and concentric with theaxis of the die), the intersecting cylindrical surfaces havingintersecting and perpendicular axes. So shaped, the die edge 23 iscapable of full circular, or interrupted full circular (Fig. 5), contactwith the work surface. Considering the depth of the element as, forexample, normal to the plane of Fig. 3, or vertically in Figs. 4 and 5,the outer portion of the body forming any single convergent facegripping ridge occurs a lesser or minor extent of the element depth, ascompared with the remaining or base extent of the element depth. Thelatter, being of substantially greater area transversely of the depthdirection of the element, affords strong foundational support for thegripping ridge or arch.

Considering typically the form of die appearing at the upper left inFig. 3, its gripping edge 23 may be regarded as comprising arches orarch segments A and B which, when the die is applied to the work, extendgenerally transversely of the work surface in full engagement therewith,to effectively hold the work against longitudinal movement in eitherdirection. Being of arch formation, the gripping edge segments present astructural form capable of assuming the extr m ly heavy work loadswithout deformation or shearing of the gripping ridge or injuriouspenetration into the work. Likewise, the second pair of segments C and Dpresent circularly arched gripping edges engageable with the cylindricalwork surface continuously and generally longitudinally thereof, topositively and strongly hold the work against rotation in eitherdirection. In this connection it is important to observe that with thework being-retainable against rotation by either of the arches C and D,it becomespossible to use a single tong for both advancing and back-offrotation of the work, and to do so more effectively than has beenpossible by any other tong die of which I am aware.

While it is possible by reason of thearch-given strength of the grippingridge and the continuity of its engagement with the work to assume heavyloads using dies individually carrying only a single gripping ridge, forthe more extreme loads it may be desirable to employ the illustratedcombination of concentric ridges in which the inner ridge t4, while'ofthe same shape characteristics as the outer gripping ridge, has itsgripping edge ofiset axially toward the base of the die, from thegripping edge 23 of the outer ridge.

In the form of the invention shown in Fig. the gripping elements areshown as fitted with a body portion it and a shank ill. The shank ti isformed with a transverse opening 32 to receive a pin which will anchorthe member in place. In this case the channel construction is identicalwith that shown in my Patent No. 2,119,731. It is also pointed out thatin the structure of Fig. 5 the circular teeth are separated radiallyinto a plurality of chisel-like teeth elements 3%. This gives the effectof a plurality of gripping teeth distributed over the surface of thegripping element but disposes the gripping edge of each tooth at anangle to torque or longitudinal strain.

It will thus be seen that the gripping elements here shown may be easilyadapted for use with all types of tools such as elevators, slips, powertongs, or the like; that they can be made rapidly and cheaply; and thatthey will have a maximum strength.

While I have shown the preferred method of making gripping elements ofthe character de scribed, and the preferred structure, it is to beunderstood that various changes may be made in the various steps of themethod and the combination, construction and arrangement of the parts bythose skilled in the art without departing from the spirit of theinvention as claimed.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

1. A heavy duty metallic gripping element insertable in an oil wellequipment gripping tool and adapted to engage a cylindrical worksurface, comprisin a body having a base portion and an outer portionforming integral protrudin gr pping arches, each arch having facesrelatively convergent to an edge and said outer portion of the elementoccupying a minor extent of the depth of the element between said edgeand the bottom of the base, said edges lying in a cylindrical surfacecorresponding substantially to the work surface, said arches including apair of oppositely curved arches extending generally transversely of thework surface to hold the work against longitudinal movement in eitherdirection, and a second pair of oppositely curved arches extendinggenerally longitudinally of the work surface to hold the work againstrotation in opposite directions and the base portion of the elementbetween'said outer portion and the bottom of the base occupying a majorextent of the depth of the element and having substantially greatercross sectional area transversely of the depth of the body than saidouter portion.

2. A heavy duty metallic gripping element insertable in an oil wellequipment gripping tool and adapted to engage a cylindrical worksurface, comprising a body having a base portion and an outer portionforming integral protruding gripping arches, each arch having facesrelatively convergent to an edge and said outer portion of the elementoccupying a minor'extent of the depth of the element between said edgeand the bottom of the base, said edges lying in a cylindrical surfacecorresponding substantially to the work surface, said arches and edgesbeing continuous and including a pair of oppositely curved archesextending generally transversely of the work surface to hold the workagainst longitudinal movement in either direction, and a second pair ofoppositely curved arches extending generally longitudinally of the worksurface to hold the work against rotation in opposite directions and thebase portion of the element between said outer portion and the bottom ofthe base occupying a major extent of the depth of the element and havingsubstantially greater cross sectional area transversely of the depth ofthe body than said outer portion.

3. A heavy duty metallic gripping element insertable in an oil wellequipment gripping tool and adapted to engage a cylindrical worksurface, comprisin a body having. a base portion carrying integralridges forming gripping arches protruding in the direction of the bodydepth, each arch having sides relatively convergent to an edge and saidedges lying in a. cylindrical surface correspondin substantially to thework surface, said arches including a pair of oppositely and circularlycurved arches extending generally transversely of the work surface 0hold the work against longitudinal movement in either direction, and asecond pair of oppositely and circularly curved arches extendinggenerally longitudinally of the work surface to hold the work againstrotation in opposite directions, and said base portion of the bodyhaving greater cross sectional area transversely of the depth of thebody than the widest portions of said ridges adjacent said base portion.

4. A heavy duty metallic gripping element insertable in an oil wellequipment gripping tool and adapted to engage a cylindrical worksurface, comprising a body having a base portion and an outer portionforming an integral protruding gripping ridge having a gripping edgelying on a line defined by the intersection of two different diametercylindrical surfaces having intersecting perpendicular axes, said ridgehaving faces convergent to said edge and said outer portion of theelement occupying a minor extent of its depth between said edge and thebottom of the base, one pair of opposite extents of said edge beingapplicable to and generally transversely of the work to hold it againstlongitudinal movement in either direction with a second pair of oppositeextents of said edge applicable to and generally longitudinally of thework to hold it against rotation in reverse directions and the baseportion of the element between said outer portion and the bottom of thebase Occupying a major extent of the depth of the element and havingsubstantially greater cross sectional area transversely of the depth ofthe body than said outer portion.

spaced intervals and having a gripping edge lying on a line defined bythe intersection of two different diameter cylindrical surfaces havingintersecting perpendicular axes, said ridge having faces convergent tosaid edge and said outer portion of the element occupying a minor extentoiits depth between said edge and the bottom of the base, one pair ofopposite extents of said edge being applicable to and generallytransversely of the work to hold it against longitudinal movement ineither direction with a second pair of opposite extents of said edge applicable to and generally longitudinally of the work to hold it againstrotation in reverse directions and the base portion of the elementbetween said outer portion and the bottom of the base occupying a majorextent of the depth of the element and having substantially greatercross sectional area transversely of the depth of the body than saidouter portion.

6. A heavy duty metallic gripping element insertable in an oil wellequipment gripping tool and adapted to engage a cylindrical worksurface, comprising a body having a base portion carrying an integralgripping ridge protruding in the direction of the body depth and ofV-cross sectional shape presenting a gripping edge lying on a linedefined by the intersection of two different diameter cylindricalsurfaces having in tersecting perpendicular axes, one pair of opposlteextents of said edge being applicable to and generally transversely ofthe work to hold it against longitudinal movement in either direction,with a second pair of opposite extents of said edge applicable to andgenerally iongi tudinally of the work to hold it against rotation inreverse directions. and said base portion of the body having greatercross sectional area transversely of the depth of the body than thewidest portion of said ridge adjacent said base portion.

7. A heavy duty metallic gripping element insertable in an oil wellequipment gripping tool and adapted to engage a cylindrical worksurface, comprising a body having a base portion carrying integrally apair of concentric gripping ridges the inner of which is offset inwardlytoward the base of the body from the outer ridge,

said ridges each having a gripping edge lying on a line defined by theintersection of two different diameter cylindrical surfaces havingintersecting perpendicular axes, one pair of opposite extents of saidedge being applicable to and generally transversely of the work to holdit against longitudinal movement in either direction, with a second pairof opposite extents of said edge applicable to and generallylongitudinally of the work to hold it against rotation in reversedirections.

WALTER A. ABEGG.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 233,964 Bear Nov. 2, 18801,471,448 Burroughs Oct. 23, 1923 1,522,804 Carlson Jan. 13, 19251,908,652 Adair May 9, 1933 2,012,337 Burns Aug. 27, 1935 2,071,637Laurent Feb. 23, 1937 2,119,731 Abegg June 7, 1938 2,213,040 DrissnerAug. 27, 1940 2,282,537 Whitney May 12, 1942 2,288,851 Sharp July 7,1942 2,301,625 Johnson Nov. 10, 1942

